Lubricating oil compositions and methods of making the same



pH value between 5.5 and 7.5.

Patented Mar. 2o,'194s LUBRIOATING 01L GOLIPOSITIONS AND DIETHODS MAKINGTHE SAME Y Herschei'G. Smith, Wallingford, and Troy L.

Pennsyl No Drawing.

Lsnsdowne, Pm, asslgnors to Gulf Oil Corporation, Pittsburgh, Pa., acorporation of Application November 25, 1941, Serial No. 420,438

8 Claims. (01. 252-51) This invention relates improvements inlubrieating oil compositions and methods of-making the same. Moreparticularly this invention is concerned with lubricating oilcompositions of acharacter adaptedto protect ferrous and other metalsurfaces to which they are applied, from rust and other types ofcorrosion, in addition to aiiording lubrication of such surfaces.

Simple mineral oil films afford limited protection to metal surfacesfrom rust and other types of corrosion, but do not afford any greatprotection under severe conditions use. Many socalled anti-rustlubricating oils have been proposed, consisting of mineral-oils withadded constituents intended to protect metallic surfaces from corrosion,tarnish or rust.

Most of them are 0! rather limited applicability,

in that while they may ail'ord satisfactory protection to one class ofmetals, they may be ineiiective, or even deleterious, with anotherclass. This shortcoming is serious for example in the case of electricmotors, where surfaces of both steel and sensitivity to moisture and airand other substances to which they are exposed. It is also found thatsome compounded oils which are effective as regards preventing rust, aredeficient in lubricating properties.

Among the objects of the present invention is lishing and, maintainingthe composition on the surfaces thereof, remain bright indefinitely, and

copper-alloy bearings (which present a diflicult problem in protectionfrom corrosion) are maintained in'their highly-finished condition even 7under unfavorable conditions of use. Copper, aluminum, zinc, tin andtheir alloys are all eiiectively guarded against corrosion and are wellhousehold lubricants, machine oils, gun oils, turbine oils, slushing.oils, and the like are prepared,

by selecting a suitable lubricating oil or base and dissolving therequired amount of the inhibitor described in the oil.

The invention finds special utility in the case of relatively light (lowviscosity) oils, for lubrithe provision of an anti-corrosive lubricatingoil composition, of excellent lubricating properties,

adapted to protect steel from rusting while being of itself free fromtendencies to corrode copper and other metallic surfaces, and being initself relatively inert and unaffected by air and molsture.

These and other objects of the invention are achieved by the provisionof a lubricating oil composition including, as a rust inhibitor, the

substantially neutral product obtained by reactfatty amines containingfrom 8 to is carbon atoms; reaction being conducted under conditionssuch that the reaction product This composition proves to be very,eflectiveas an anti-corrosion lubricant, ior metal suriaces in general.It forms a tightly adherent oily film on.

the metal, protecting the surface from moisture and air, In addition,the composition itself is tree from any tendency toattack the metal, byreaction. therewith or otherwise. Polished or highly-finished steelsurfaces protected by estabormixturehasa -i ng isoamyl octyl acidphosphate with primary cating light mechanism such as electric fans,guns, etc. For example, the invention is especially well suited forimproving highly refined lubricating oils, of Saybolt Universalviscosity about to 150 at R, oils of 100' viscosity beingespeciallysuitable.

Usually 0.5 per cent or less of the inhibitor is sufllcient to impart tolubricating oils adequate rust-inhibiting properties for articlesexposed to moisture and air, but as much as 25 per cent by Y weight onthe oil is sometimes incorporated to aflord prolonged and completeprotection fromrust under extremely severeconditions. Such cellentlubricating and other characteristics in addition to ailordingpractically complete rust protection under extraordinary conditions.

' The reaction products employed in the present invention are relativelystable compositions un-- der ordinary conditions. At'room temperaturessome of them are heavy viscous liquids, others soit solids which melt tooily liquids at slightly elevated temperatures. All are relatively non-jvolatile, and are insoluble in water and more or less water repellant.They are very resistant to hydrolysis. The reaction products arehoweversoluble in 0. both mineral oils and fatty oils. The solubility variessomewhat with the particular oil, but is quite high in general. 1

. In preparing our rust inhibitors, the isoamyl octyl acid phosphate iscaused to react with the primary fatty amine in approximately equal mo-',lecular ratios, and the reaction is controlled'so as to producesubstantially neutral reaction mixpared by known methods and any of thecommercial acid esters may be employed. This acid ester is a di-ester oiortho-phosphoric acid and has the following formula:

' n n n o n n mc--te-d-o-ko-d-d-cmi H: H 1 H H 1H0 This compound is alsoknown as 3-methyl-butyl,

Z-ethyl-hexyl ortho-phosphate.

The primary fatty amine employed to react with the acid phosphate estermay be represented by the following generic formula:

HrN-CH:( CH!) a-CH:

' wherein n is an even number between 8 and 16.

. I". after mixing the two components. To the This generic classincludes the following membars: 7 Mono-capryl amine, canon cuminMono-lauryl amine, CH; (CH1) roCHa'NH:

Mono-myristyl amine, CH3(CHz)1sCHaNI-I2 Mono-palmityl amine, CHaiCHz)uCHsNHa Mono-stearyl amine, CH:(CH:)10CH:NH2

We sometimes prepare the rust inhibitors by reaction of the ester withsome particular one of these amines, but more usually mixtures of aminesof this group are employed, as they afford a somewhat better productthan if only one amine is used. One commercially available mixture whichwe ordinarily employ is so-called coco amine, made in known ways byconversion of coconut oil fatty acids into the corresponding amines.Coco amine contains a molar amount of mono-lauryl amine (the C1: amine)with minor amountsof its adjacent homologs. The average molecular weightof coco amine ranges between 200 and 210. A value within this range isconsidered as the molar weight in reacting with the ester.

The following example illustrates one good way of preparing a rustinhibitor within the purview of the present invention.

Example I.'I'o a suitable vessel equipped with heating and cooling coilsand means for mechanical agitation are added 200 pounds of coco amine,and 281 pounds of isoamyl octyl acid phosphate, commercial grade, areslowly added, slowly so 'as to keep the temperature of the reactionmixture below 180 F. whereby to avoid splitting out water from themixture. After the addition of isoamyl octyl acid phosphate, the mixturehas a tained in Example I is soluble in mineral oils,

as are the amines from which it is prepared. Accordingly, we sometimesprepare concentrated solutions of the rust inhibitor in mineral oil byforming them in situ in the oil. In such processes, the fatty amine isfirst dissolved in the mineral oil, and then the acid phosphate esteradded, the mixture being stirred and maintained at desired temperaturesuntil the reaction is complate and the mixture has a pH value within thespecified. range. In preparing the oil concentrate, sometimes additionalamine is added in the later stages to adiust the pH value as desired.Preparation ofsu'ch a concentrated rust inhibitor is illustrated in thefollowing example:

above mixture 175 pounds of isoamyl octyl acid phosphate were added overa period of two hours. The mixture was agitated with air during theaddition and the temperature rose to 185 F. The pH of the mixture atthis stage was 3.4. To increase the pH of the mixture, 5 pounds of cocoamine were added, which increased the pH from 3.4 to 4.0. Another 4pounds of coco amine were added to bring the pH into a higher range, and

the pH after this addition was 6.0. Finally 5 pounds more of the cocoamine were added to the mixture, which gave a final pH of 6.7. The abovemixture, after the final pH adjustment, was added to the mineral oil.

The reaction products prepared as described above may be dissolved invarious types of min eral oils and improved anti-rust and non-corrosiveoil compositions obtained capable of inhibiting or retarding the rustingof ferrous metals as described.

Example III.-In preparing an oil especially suitable for lubricatinghousehold appliances or instruments, the rust inhibitor of the classdescribed is dissolved in a refined paraflinic oil hav- Base oilImproved oil Gravity, API lsoosity, SUV, 100 F Color, Baybolt These oilswere then tested for non-rusting properties by the following test:Thirty-six cc. of the oil to be tested and 4 cc. of water are placed in,a l" x 8" Pyrex test tube, and a polished copper or steel strip isimmersed in the oil-water mixture; 2000 cc. of humidified air per. hourare bubbled through the mixture, so as to provide mixing of the oil andwater. The apparatus is set in a water bath maintained at 122 F. C.) andthe original water level in the tube is main tained by additions offresh water every 24 hours. The test is continued for 12 days,regardless of whether or not the strip shows signs of corrosion. Thebase oil began to show rust on a steel strip after 6 hours in the testwhereas after 12 days the improved oil showed no evidence of rust.0rdinarily an uninhibited oil will tarnish a copper strip withinapproximately twelve hours, and will attack a steel strip. Generally theaddition of as little as 0.05 per cent by weight of a rust inhibitorsuch as alkylamine isoamyl octyl phosphate, will maintain both thecopper and thelsteel strips free from tarnish and rust for periods up totwelve days, the maximum duration of the test. The test may be carriedout with copper, steel, or other metallic strips, such as zinc and tin.

In certain special cases the prevailing conditions are so extreme as torequire that a lubricant be extremely highly protective toward metalsurfaces. In this case a higher percentage of rust inhibitor isincorporated in the oil.

Example IV.-In preparing one such lubricant,

Example II.-One hundred pounds r 1mm 1" as per cent of the rustinhibitor-was incorporated.

asraeei The oil base selected and the improved lubricant made from ithave the following properties:

Base oil Improved oil Gravity, API E. 28. 4 Viscosity, SUV, 100 F 110109 Color, N PA l. 25 l. 25

This oil is capable of preventlngrusting and corrosion of metals underextreme conditions,

even in the presence of salt or sea water. In.

testing it an aqueous solution of salt is substituted for the wateremployed in the test given above. the procedure otherwise being thesame. Both the base oil and the improved oil were tested.

The improved oil showed no evidence or corroding either copper or steelafter 12 days in either of the above tests, whereas the base oil allowedthe steel strip to rust in approximately 8 hours in the fresh water testand in about 3 hours in the salt water test. The copper strips were moreslowly attacked, but overnight were coated with a greenish deposit.

The specific embodiments described above are merely illustrative of thepractice of this invention and other embodiments thereof may be used asdesired; for instance, these rust inhibitors are compatible with variousother compounding ingredients and they may be added to blended oil basesor compounded lubricants to obtain other types of improved lubricants.Improved oil compositions can be prepared from base oil containthe opumresults for a given not of the agent in oil are secured when the pHvalue is mainted wi the stated range of 5.5 to 7.5 for the compoundingagent. There is usuall a slight drop in pH value in the dilute finishedoil solution as compared with the values for the compoding agents ormixtures thereof. The "i ..;;.1 ed oil (which usually contains only asmall should test between 5.0 and 6.0; advantageously around 5.7.

Any substantial departure from the stated re either on the alkaline oracid side gives less desirable results. For example, with an unduly lowpH value (acid-side) there is some rustins of steel surfaces by oursteel'strlp corrosion test, while compositions with an excessivel highvalue (alkaline side) may produce greenish cor rosion effects by theoxidation tests with copper surfaces and'the like, although notafiecting steel to any appreciable extent. The exact adjustment isattained'in preparing the compound (e. g. cocoamine salt of isoamyloctyl phosphate) by reacting the desired molecular proportions of thetwo agentsinthe manner described, and after the neutralization orcompounding reaction has progressed practically to completion, bytesting the ing varying amounts of fatty oils admixed with mineral oil,such blends being especially useful as household lubricants. By thepresent invention, any of the previously known household or otherlubricants containing relatively light lubricatng oils can be improvedby adding small amounts of our rust inhibitors as described.

The invention is equally applicable to heavy mineral oils, petrolatumoils. greases, and jellies;

in fact to any petroleum lubricant ,or coating oil,

in which corrosion-preventive properties are desired. In the claims theterm lubricant includes mineral oils, jellies and the like even whenused for purposes other than strict lubrication; e. g. slushing oils andgun greases.

One important application of the present invention is to the preventionof rusting in aviation engines after these have been used, either uponaging inintermittent actual service or in storage of engines or planesawaiting completion of assembly, shipment, and other delays after enginebreak-in. Such rusting is aggravated by the presence in 'the crankcaseand crankcase-0110i reaction product, and making any minor adjustmentsthat are necessary for exact control by adding the required smalladditional proportion of the amines (if on the acid side of our desiredrange) or the isoamyl octyl phosphate (if on the alkaline side) Inmeasuring the pH of the agents of the present invention and oilscontaining them, which are both substantiallywater-insoluble, the sambyelectrometric or colorimetric procedures; the.

sion thereof in the presence of moisture and air,

comprising a. petroleum lubricant containing in solution in a proportionsumcient to prevent rust ind, a substantially neutral addition productof 3-methyl-butyl, 2j-ethylhexyl acid phosphate and a primary fattyamine containing from 8 to 18 moisture, Sulfur, oxidation products frompetroleum, tetraethyl lead, decomposition products, etc. Attempts havebeen made to remedy this conditionby washing out all motor oil from thecranh= case of 'an engine if it is to be stored for any appreciabletime, or adding compounds containing .large amounts of oiliness agentsand the like.

The present invention presents a more economical remedy for theseconditions, for corrosion iseifectively retarded under such conditionswhen from 0.5 to 1.0 per cent by weight of our compounds is added to aused motor oil. Adding-the highly potent rust preventive compound duringthe latter part of the break-in period for the new engine, withoperation for sufficient time after addition to assure .full mixing andcoating of parts, will prevent rusting.

Extensive tests in which the pH values of the agent of the presentinvention as employed in tinished oils were varied confirm our discoverythat carbon atoms, said product having a pH between 5.5 and 7.5 and conethe said acid phosphate and amine chemically combined together in molarratios between 1:1 and 1:l.l.

2. The compositio oi' claim 1 wherein said amineiscocoamine.

s. The composition of claim 1 wherein said p troleum lubricant containsfrom 0.01 to 25 per cent of said substantially neutral addition productdissolved therein.

4. A composition effective as a lubricant for metal'surfaces and capableof preventing corrosion thereof in the presence of moisture and air,comprising a. mineral oil containing in solution I from 0.01 to 25 percent of'a substantially neutral addition product or 3-methyl-butyl,2-ethyl-hexy1 acid phosphate and a primary fatty amine containlng from 8to 18 carbon atoms, said product having a pH.between 5.5 and 7.5 andcontaining the said acid phosphate and amine chemically combinedtogether in molar ratios between 1:1

and 1; 1.1.

ropoition of the dilute compounding agent) 5, A lubricating oil formetal surfaces capable of preventing corrosion thereof in the presenceof moisture and air comprising a mineral 011 containing between 0.01 and0.5 per cent of a substantially neutral addition product of3-methylbutyl, z-ethyl-hexyi acid phosphate and a primary fatty aminecontaining from 8 to 18 carbon atoms, said product having a pH between5.5 and 7 .5 and containing thesaid acid phosphate and amine chemicallycombined together in molar ratios between 1:1 and 1: 1.1.

6. A method of preparing an oily composition, useful as a rustpreventive lubricant, which comprises admixing with a mineral oil atleast one primary fatty amine containing 8 to 18 carbon ,atoms,dissolving in said mixture an equimolecular quantity of 3-methyl-butyl,Z-ethyl-hexyl acid phosphate and maintaining the oil solution ofreactants at a temperature between 80 and 185 F. until the reaction issubstantially complete and then adjusting the pH of the reaction mixtureto within the range 5.5 to 7.5 by the further addition of approximately0.1 mole of said amine.

7. The method of claim 6 wherein said primary fatty amine is cocoamine.

8. A method of preparing lubricant compositions, capable of preventingcorrosion oi steel and, other metal surfaces in the presence of moistureand air, which comprises dissolving in mineral oil at least one primaryfatty amine containing 8 to 18 carbon atoms, gradually adding anequimolecular quantity of 3-methyl-butyl, 2-ethylhexyl acid phosphate tothe oil solution of said amine, at such a rate as to control thevigorous exothermi: reaction and maintaining the reac-' tion mixturebelow 185 F., agitating the oil solution of said. reactants at suchtemperatures until the reaction is substantially complete, and thenadjusting the pH of the reaction product to within the range 5.5.to 7.5by the further addition of approximately 0.1 mole of said amine.

nnnscnm. 6. SMITH. \TRQY n CAN'I'RELL.

